Effect of frontal slope on waveform evolution of a depression interfacial solitary wave across a trapezoidal obstacle

► We modeled evolution of an ISW across a trapezoidal obstacle with four front slopes. ► Front slopes used in the laboratory vary from mild (13°) to very steep and vertical. ► Video footage reveal temporal and spatial variations of the interface of ISW motion. ► Outcome of waveform inversion on a plateau reduced due to steepening of front slope. ► Variation in active wave period during evolution was detected by Hilbert transform.